Question

我有一个程序，我使用向量为结构创建n个对象。我想将这个向量传递给函数get_stud_data，我输入了学生的名字。我想要并将所有矢量对象返回到主函数

#include <iostream>
#include <string>
#include <vector>
#include "stdio.h"

using namespace std;

struct students
{
string name; // I am not sure
int roll_no;
};

vector<p>& get_stud_data(vector<students> & p, int n)
{
for(int i=0;i<n;i++)
{
cout<<"Enter Name of " <<i+1<<"th student\n";
cin>> p[i].name;
}
return p;
}

int main()
{

int n;
cout<<" Enter the number of students: ";
cin>> n;

vector<students> p(n); // creating n objects for struct students

  // Want to retrieve the objects here.
    p=get_stud_data()
    return 0;

    }

Answer 1

你不需要。您将向量作为引用传递，以便您的函数可以更改它：

return this.connectivityService.isOnline()
  .flatMap((isOnline: boolean) => {
    if (isOnline) {
      return Observable.of(); // subscribe() is not called
    } else {
      return Observable.throw(new OfflineError('The device is offline.'));
    }
  })
  .do(() => console.log('Do things here'));

如果你真的想要返回一个矢量，你可以。在这个练习中，这是毫无意义的，因为那时你有两个：

#include <iostream>
#include <string>
#include <vector>

using namespace std;

struct student
{
  string name;
  int roll_no;
};

void get_student_data(vector<student>& students)
{
  for(int i = 0; i < students.size() ; i++ )
  {
    cout << "Enter Name of " << i+1 << "th student\n";
    cin >> students[i].name;
  }
}

int main()
{
  int n;

  cout << " Enter the number of students: ";
  cin >> n;

  vector<student> students(n); 

  get_student_data(students);

  // cout some students here to see it worked

  return 0;
}

Answer 2

如果您真正想要的是阅读n个学生的矢量并将其返回给来电者，您可以这样做：

{
  "private": true,
  "scripts": {
    "prod": "gulp --production",
    "dev": "gulp watch"
  },
  "devDependencies": {
    "bootstrap-sass": "^3.3.7",
    "gulp": "^3.9.1",
    "jquery": "^3.1.0",
    "laravel-elixir": "^6.0.0-11",
    "laravel-elixir-vue-2": "^0.2.0",
    "laravel-elixir-webpack-advanced": "*",
    "laravel-elixir-webpack-official": "*",
    "lodash": "^4.14.0",
    "multiselect": "^0.9.12",
    "node-sass": "^3.10.0",
    "notifyjs-browser": "^0.4.2",
    "sweetalert": "^1.1.3",
    "vue": "^2.1.0",
    "vue-resource": "^1.0.2",
    "vue-router": "^0.7.13",
    "vuetable-2": "^1.2.0",
    "vuex": "^2.1.1",
    "whatwg-fetch": "^1.0.0",
    "wow.js": "^1.2.2"
  },
  "dependencies": {
    "laravel-echo": "^1.0.5",
    "pace": "0.0.4",
    "pace-js": "^1.0.2",
    "pusher-js": "^3.2.1"
  }
}

此外，我在您的代码中注意到您创建了给定大小为n的向量，并将其传递给函数以读取其内容。因此，如果您真的想要创建给定大小的向量，并让该函数只读取该向量中的学生数据，您只需将vector<student> get_student_data(int n) { vector<student> v(n); for (int i = 0; i < n; i++) { cout << "Enter Name of " << (i+1) <<"th student\n"; cin >> v[i].name; } return v; }作为输入/输出参数传递（使用reference：{{ 1}}），没有指定额外的vector<student>参数，因为向量知道自己的大小（例如，您可以使用vector<student>&查询）：

int n

将矢量对象传递给函数并返回

2 个答案: